To create this kind of effects people have used dummy heads with microphones attached to ears of this head. If I understand it correct is about different filtering of sounds if they are in front, back, up, down, or in side of you. I guess this kind of thing would be able to do with some kind of convolution effect? Or maybe two filters modelled after ears. Something like vowel filter but in this case made after cavities of ears.
I guess it would work well only if someone is listening with headphones. And I think it works best there is some movement in sound like the sound source is moving around you.

I have no idea if anyone has made this kind of plug-in.

edit. I have heard it does not work so good iwith everyone. If your ears are very different from dummys, you dont experience it as coming from different places around you. I guess you learn during your lifetime from where sound seems to be coming.

Metanol wrote:For moving sound they had to be somehow synced or automated.

I'm talking about a static effects. Sorry about the confusion.

I just played around with a plugin pertaining to the topic, MStereogenerator. In a way it's a glorified reverb but it but as such it has a distinctive and unique sound that I can see myself using on stuff I want to keep center panned. The downside is that it can't be used as a send effect(wtf?).